Paleoepidemiology of trauma in a prehistoric 

 central California population 



Robert D. Junnain 



1 he challenges faced by and the personal catastrophes that 

 beset prehistoric peoples sometimes fortuitously leave traces 

 in their skeletons. One of the better perspectives from which 

 to obtain data concerning particularly challenging events in 

 the archeological past is the analysis of traumatic lesions. 



Several researchers have noted previously that evidence of 

 fractures, projectile wounds, and dislocations can provide 

 information concerning the incidence of accidents or inter- 

 personal violence in prehistoric populations (Elliot-Smith 

 and Wood-Jones 1910; Angel 1974; Edynak 1976; Lovejoy 

 andHeiple 1981). 



A large and very well preserved skeletal collection from 

 the prehistoric central Califomian site of Ala-329 offers fur- 

 ther illumination concerning traumatic episodes in the past. 

 Differential diagnosis and analysis of traumatic lesions in this 

 skeletal population provide examples of severe accidents as 

 well as many cases of interpersonal violence. In addition, 

 comparison of reactive changes about the hip joint seen in 

 this group help further clarify the distinction between trau- 

 matic and congenital hip dislocation. 



Materials and methods 



Ala-329 is a large shell mound site located on the eastern 

 shore of San Francisco Bay, approximately 20 miles north of 

 San Jose. While now located approximately 2 '/2 miles in- 

 land, the site probably once stood adjacent to the bay shore 

 surrounded by saltwater marshes. Newly determined radi- 

 ocarbon dates chronologically place the site between at least 

 A.D. 500 and European contact (approx. a.D. 1700). 



Ala-329 is a large site with dimensions extending 133 x 

 90 X 4 m high, and no doubt contains hundreds of burials. 

 Excavations carried out by Stanford University and San Jo.se 

 State University mostly during the 1960s exposed 20-25% 

 of the mound and still removed 440 burials. The sample 

 available for analysis in this study includes the 420 grave lots 

 (representing a minimum of 440 individuals) excavated be- 

 tween 1959 and 1968 by San Jose State University and Stan- 

 ford University field classes. Of these, the most relevant 

 group for the present study is the 248 aged and sexed 



Zofireh Pateopalhnlof^y Symp. 1988 



adults — 138 males and 1 10 females. Overall, the condition 

 of the burials is good to excellent and. as such, this collection 

 represents one of the larger and better preserved osteological 

 samples in the western United States. 



Moreover, most graves were undisturbed, and careful ex- 

 cavation retrieved many elements intact. Indeed, more than 

 one-third of all burials could be described as "complete" 

 (i.e., containing most major elements intact). Soil conditions 

 at this site, apparently physically and chemically buffered by 

 the large quantity of shell, afforded excellent conditions for 

 preservation (see Figure 1). 



Pathological lesions were diagnosed by gross macroscopic 

 examination and supported by radiographic analysis includ- 

 ing standard x-ray as well as computed tomography (CT) 

 scans. In most cases the diagno.ses from gross specimens and 

 radiographs were corroborated through examination by an 

 orthopedic surgeon. Most fractures were ascertained by the 

 presence of angular deformity often accompanied by short- 

 ening of the affected element. In other cases, in the absence 

 of gross morphological change, a diagnosis of healed frac- 

 ture could not be supported unequivocally. Indeed, detailed 

 examination of more than 100 radiographs of long bones by 

 the author as well as an orthopedic surgeon could not find one 

 additional healed fracture. Long-standing, very well healed 

 fractures with no deformity or shortening are thought by 

 many researchers to be virtually impossible to detect. Some 

 reports (notably. Lovejoy and Heiple 198 1 ) have relied upon 

 subtle radiographic criteria to support diagnoses of most trau- 

 mas. While such evidence may. in fact, be applicable to some 

 specific cases, the ultimate effect will be to raise the apparent 

 fracture rate in those samples to which such criteria have 

 been applied, as compared to those groups (e.g., Ala-329) 

 where such diagnoses are not supported. 



Results and discussion 



After dental disease and degenerative involvement ( Jurmain 

 1983), trauma is the most common type of pathological le- 

 sion seen in this population. In many circumstances it is not 

 possible to differentiate trauma from degenerative joint dis- 



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